Groningen Venous Imaging Study
Comparing Ultrasonography with MRI for Evaluation of Presence of Deep Vein Thrombosis
Part 1 - Pilot Study

Accurate diagnosis of deep vein thrombosis (DVT) is important to prevent
thrombo-embolic complications on the one hand and to avoid unnecessary
anticoagulant treatment on the other hand. Ultrasonography is currently
clinical routine in the diagnostic work-up of DVT. Although ultrasonography can
diagnose a first episode of proximal (vena femoralis until vena poplitea) DVT
accurately, it has several limitations. Often, repeated examinations are needed
to detect or exclude DVT and a number of patients eventually undergo MRI
examination.

MRI has several advantages over compression ultra sound (CUS). First, MRDTI can
evaluate recent and active thrombus formation, in particular when recurrent DVT
is suspected. The new MRDTI sequence thus has the potential to differentiate
between remnant abnormalities from a previous episode of DVT and a newly formed
thrombus, which may have consequences for the need for anticoagulant treatment.
Second, MRI has the possibility of imaging the full venous course from pelvic
to calf veins.

We aim to evaluate the use of MRDTI in the diagnosis of acute proximal DVT,
comparing the findings with CUS. To evaluate the outcome of patients with
positive and negative MRDTI and CUS, clinical outcome after 3 months of
follow-up will be measured.
The hypothesis of this study is that MRDTI is at least as good as CUS in
diagnosing DVT in terms of sensitivity, specificity, diagnostic time interval
and number of examinations needed.

This pilot study is a prospective observational pilot study, with an estimated
inclusion time of three months and a number of patients needed of 40.
Patients who present at the emergency department with clinical suspicion of DVT
and who are eligible to enter the study will be approached for inclusion.
Written informed consent will be obtained.
CUS will be performed upon presentation, as in normal clinical practice.
Hereafter, the patient will be scheduled for MRI, preferably while still in the
Emergency Room, but at least in 24 hours.
As in routine clinical practice, patients with a proven DVT by CUS will be
treated accordingly with anticoagulants by physicians of the department of
Hematology, irrespective of the outcome of MRDTI. Thus, the result of the MRDTI
will not be considered for treatment. However, patients with a negative CUS and
a positive MRDTI will be treated according to the MRDTI, as we would do in
normal clinical practice when suspicion of DVT is high but (repeated) CUS is
negative.
All patients are seen after three months at the outpatient clinic of Hematology
to assess clinical outcome. However, patients with proven DVT are more
frequently seen, as in normal clinical practice (at two weeks, three months and
six months after diagnosis of DVT). When a patient returns to the hospital due
to persistent complaints or new suspicion of DVT despite negative prior
examinations, both ultrasound and MRDTI will be repeated. After inclusion of 40
patients, the pilot study will be closed, and analysis will be performed.

Risks of ultrasonography: none documented. Risks of MRDTI: none documented.
The burden for patients included in the study will consist of one non-invasive
examination by MRI for every examination by ultrasonography, which may thus
involve one extra visit to the hospital or extra waiting time.